It really depends on the plane. If you've got a WWI plane, there's almost as many different props as there were planes. I think what you mentioned about carving a functional wood prop is about as good as anything, as long as the scale prop is 2-bladed. I carve one blade and get it looking like what I want, then trace a template of the profile so I can match the other blade to the first. There are commercially available static props available, but the selection is probably limited.